This project is concerned with the identification and characterization of components which are lung specific or pulmonary disease-related which could be used as diagnostic markers for pulmonary damage or disease. Current attention is being focused on: 1) the soluble alkaline phosphatases of the normal lung, 2) abnormal hydrolases present in pulmonary lavage effluents from patients with alveolar proteinosis, and 3) enzymic components of human amniotic fluid which originate in the fetal lung.